Optical Physiological Sensor Modules with Reduced Signal Noise

ABSTRACT

An optical sensor module for detecting and/or measuring physiological information that can be integrated into a wearable device, such as a headset, a wristband, a ring, etc., includes a housing supporting an optical source and an optical detector. The housing overlies the optical source and optical detector and includes a first light guide comprising light transmissive material in optical communication with the optical source and a second light guide comprising light transmissive material in optical communication with the optical detector. The first and second light guides define respective first and second axial directions that are outwardly diverging. When the sensor module is in use and placed adjacent the skin of a user, light rays emanating from the optical source and directed into the skin of the user cannot overlap with light rays returning through the skin of the user.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 62/033,922 filed Aug. 6, 2014, the disclosure ofwhich is incorporated herein by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to monitoring devices and, moreparticularly, to optical sensor devices.

BACKGROUND OF THE INVENTION

There is growing market demand for personal health and environmentalmonitors, for example, for gauging overall health and metabolism duringexercise, athletic training, dieting, daily life activities, sickness,and physical therapy. However, traditional health monitors andenvironmental monitors may be bulky, rigid, and uncomfortable—generallynot suitable for use during daily physical activity.

Sensors for detecting biometric signals, such as vital signs and otherphysiological information, are configured to isolate the biometricsignals from other spurious signals and deliver biometric readings, suchas heart rate, respiration rate, blood pressure, etc., to the user.Unfortunately, spurious signals that may be difficult to isolate from abiometric signal are associated with physical movement (e.g., physicalexercise, such as walking, running, daily activities, etc.) of a sensorrelative to the user or the environment of the user (e.g., sunlight,room light, humidity, ambient acoustical or electromagnetic noise,temperature extremes or changes in temperature, etc.).

For example, referring to FIG. 1, a conventional photoplethysmography(PPG) optical sensor 10 is illustrated that includes an optical source14, and an optical detector 16. The optical sensor 10 is desirablypositioned directly against the body B (i.e., the skin) of a subjectwearing the optical sensor such that light L₁ from the optical source 14is directed into the body B and is subsequently detected by the opticaldetector 16. However, movement of the user can cause the sensor 10 tomove relative to the body B such that light L₂ can take a direct pathfrom the optical source 14 into the optical detector 16 (for example byreflection off of the body, i.e., the skin, of the user), whichincreases spurious signals. Moreover, motion artifacts may cause thedistance between the sensor 10 and body B to change in time, therebymodulating L₁ and L₂ in time, leading to motion artifact noise on thesignal generated by the detector 16.

Previous ways of isolating heart rate signals from other signals includethe use of passive and active signal processing algorithms, increasingoptical sensor output and displacing the optical source from thephotodetector, and pushing the sensor more firmly against the user so asto limit the effects of physical movement on the heart rate signal.

SUMMARY

It should be appreciated that this Summary is provided to introduce aselection of concepts in a simplified form, the concepts being furtherdescribed below in the Detailed Description. This Summary is notintended to identify key features or essential features of thisdisclosure, nor is it intended to limit the scope of the invention.

According to some embodiments of the present invention, a wearableoptical sensor includes at least one optical emitter, at least oneoptical detector and light-guiding optics. The light-guiding optics areconfigured to direct a beam pattern of light upon a body of a subjectwearing the optical sensor and to detect light scattered from adetection region of the body. In addition, the light-guiding optics areconfigured to prevent overlap between the beam pattern of light and thedetection region when the wearable sensor is separated from the body,for example, by a distance up to about three tenths of a centimeter (0.3cm). In some embodiments, the light-guiding optics includes opticalfiltering material and/or light polarizing material.

According to some embodiments of the present invention, an opticalsensor module for detecting and/or measuring physiological informationfrom a subject and that can be integrated into a wearable device, suchas a headset (e.g., an earbud, etc.), an armband, a wristband, clothing,foot apparel, a ring, etc., includes a base and a housing secured to thebase. The base includes an optical source and an optical detector. Thehousing overlies the optical source and optical detector and includes afirst light guide comprising light transmissive material in opticalcommunication with the optical source and a second light guidecomprising light transmissive material in optical communication with theoptical detector. The first and second light guides define respectivefirst and second axial directions that are outwardly diverging. Thefirst axial direction of the first light guide is angled relative to aplane defined by a surface of the optical source, and the second axialdirection of the second light guide is angled relative to a planedefined by a surface of the optical detector. When the sensor module isin use and placed adjacent the skin of a user, a substantial majority oflight rays emanating from the optical source and directed into the skinof the user cannot overlap with light rays returning through the skin ofthe user and collected by the second light guide when the housing isseparated from the skin, for example, by a distance up to about threetenths of a centimeter (0.3 cm).

In some embodiments, at least one of the first and second light guidesis cylindrical. In other embodiments, at least one of the first andsecond light guides is non-cylindrical.

The first and second light guides include opposite proximal and distalends. In some embodiments, the proximal and distal ends of at least oneof the first and second light guides have different sizes. For example,the diameter of a light guide distal end may be greater than a diameterof the proximal end thereof. Alternatively, the diameter of a lightguide distal end may be smaller than a diameter of the proximal endthereof. In some embodiments, the proximal and distal ends of at leastone of the first and second light guides may have differentconfigurations. For example, the proximal end of a light guide may haveone type of geometric configuration and the distal end may have adifferent geometric configuration. As an example, the proximal end mayhave a triangular configuration and the distal end may have arectangular configuration, etc.

In some embodiments, the distal end of at least one of the first andsecond light guides has a curved surface. In other embodiments, thedistal end of at least one of the first and second light guides has atextured surface.

In some embodiments, multiple light guides may be substituted for asingle light guide either on the optical source or over the opticaldetector.

In some embodiments, single or multiple light guides may be placed overmultiple optical sources or multiple optical detectors.

Optical sensor modules according to embodiments of the present inventionare advantageous because they can lower the sensitivity of an opticalsignal to sensor-user movement related noise, thereby enabling asignificant improvement in heart rate monitoring consistency acrosssubjects and types of exercise activities.

According to some embodiments of the present invention, a headsetincludes a base comprising an optical source and an optical detector,and a housing that is secured to the base and is configured to bepositioned at or within an ear of a subject. The housing overlies theoptical source and optical detector and includes a first light guide inoptical communication with the optical source and a second light guidein optical communication with the optical detector. The first and secondlight guides define respective first and second axial directions thatare outwardly diverging.

According to some embodiments of the present invention, an opticalsensor module includes a base having an optical source and an opticaldetector, a housing secured to the base that overlies the optical sourceand optical detector, and at least one light polarizing element inoptical communication with the optical source and the optical detector.The at least one polarizing element is configured to polarize lightemitted by the optical source and/or polarize light detected by theoptical detector.

In some embodiments, the at least one light polarizing element is alight polarizing film, a light polarizing lens, and/or a lightpolarizing light guiding material in the optical path of the opticalsource and/or the optical detector.

In some embodiments, the at least one light polarizing element includesa first light polarizing element in optical communication with theoptical source and a second light polarizing element in opticalcommunication with the optical detector. The first and second lightpolarizing elements may have the same light polarization orientation ormay have respective different light polarization orientations.

In some embodiments, the sensor module housing includes at least onewindow through which light from the optical source passes and/or throughwhich light detected by the optical detector passes. The at least onewindow includes the at least one polarizing element. For example, the atleast one window may include a first window in optical communicationwith the optical source and a second window in optical communicationwith the optical detector. The first window includes a polarizingelement (e.g., a polarizing film, etc.) and the second window includes apolarizing element (e.g., a polarizing film, etc.). The first and secondwindow polarizing elements may have the same light polarizationorientation or may have respective different light polarizationorientations.

According to other embodiments of the present invention, an opticalsensor module for detecting and/or measuring physiological informationfrom a subject includes a base having an optical source and an opticaldetector, and a housing secured to the base that overlies the opticalsource and optical detector. The housing includes a first light guide inoptical communication with the optical source and a second light guidein optical communication with the optical detector. The first lightguide includes light polarizing material that is configured to polarizelight emitted by the optical source, and the second light guide includeslight polarizing material that is configured to polarize light detectedby the optical source. The first light guide light polarizing materialand the second light guide light polarizing material may have the samelight polarization orientation or may have respective different lightpolarization orientations.

According to other embodiments of the present invention, an opticalsensor module for detecting and/or measuring physiological informationfrom a subject includes a housing, an optical source supported by thehousing, an optical detector supported by the housing, and at least onelight polarizing element supported by the housing. The at least onelight polarizing element is configured to polarize light emitted by theoptical source and/or polarize light detected by the optical detector.In some embodiments, the at least one light polarizing element is alight polarizing film, a light polarizing lens, and/or a lightpolarizing light guiding material in the optical path of the opticalsource and/or the optical detector.

In some embodiments, the at least one light polarizing element includesa first light polarizing element in optical communication with theoptical source and a second light polarizing element in opticalcommunication with the optical detector. The first and second lightpolarizing elements may have the same light polarization orientation ormay have respective different light polarization orientations.

In some embodiments, the sensor module housing includes at least onewindow through which light from the optical source passes and/or throughwhich light detected by the optical detector passes. The at least onewindow includes the at least one polarizing element. For example, the atleast one window may include a first window in optical communicationwith the optical source and a second window in optical communicationwith the optical detector. The first window includes a polarizingelement (e.g., a polarizing film, etc.) and the second window includes apolarizing element (e.g., a polarizing film, etc.). The first and secondwindow polarizing elements may have the same light polarizationorientation or may have respective different light polarizationorientations.

According to other embodiments of the present invention, an earbudincludes a speaker driver, and a sensor module secured to the speakerdriver that is configured to detect and/or measure physiologicalinformation from a subject wearing the earbud. In some embodiments, thesensor module includes a printed circuit board (PCB), an optical sourcesecured to the PCB, and an optical detector secured to the PCB. In someembodiments, the PCB is an elongated, flexible PCB having a distal endportion, and the optical source and optical detector are secured to thePCB at the distal end portion.

In some embodiments, the earbud includes a first light guide coupled tothe optical source and a second light guide coupled to the opticaldetector. The first light guide is configured to deliver light from theoptical source into an ear region of the subject via a distal endthereof, and the second light guide is configured to collect light fromthe ear region via a distal end thereof and deliver collected light tothe optical detector.

In some embodiments, the earbud includes one or more additional sensorssecured to the speaker driver. Exemplary additional sensors include, butare not limited to, accelerometers, humidity sensors, altimeters, andtemperature sensors.

In some embodiments, the earbud includes at least one signal processorconfigured to process signals produced by the optical detector. In otherembodiments, the earbud is in communication with a data processing unitthat is configured to process signals produced by the optical detector.

According to other embodiments of the present invention, a monitoringdevice includes a band capable of at least partially encircling aportion of a body of a subject, and an optical source and an opticaldetector supported by the band. The band includes a first light guide inoptical communication with the optical source and a second light guidein optical communication with the optical detector. The first and secondlight guides define respective first and second axial directions, andthe first and second axial directions diverge outwardly from the band.In some embodiments, the first and second light guides are angledrelative to each other such that light rays emanating from the opticalsource and directed into the skin of the subject via the first lightguide cannot overlap with light rays collected by the second light guideeven when the housing is separated from the ear by a distance up toabout three tenths of a centimeter (0.3 cm). In some embodiments, thefirst axial direction of the first light guide is angled relative to aplane defined by the optical source, and the second axial direction ofthe second light guide is angled relative to a plane defined by theoptical detector.

It is noted that aspects of the invention described with respect to oneembodiment may be incorporated in a different embodiment although notspecifically described relative thereto. That is, all embodiments and/orfeatures of any embodiment can be combined in any way and/orcombination. Applicant reserves the right to change any originally filedclaim or file any new claim accordingly, including the right to be ableto amend any originally filed claim to depend from and/or incorporateany feature of any other claim although not originally claimed in thatmanner. These and other objects and/or aspects of the present inventionare explained in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which form a part of the specification,illustrate various embodiments of the present invention. The drawingsand description together serve to fully explain embodiments of thepresent invention.

FIG. 1 is a side section view of a conventional optical sensorillustrating how light can take a direct path from an optical source toan optical detector via reflection off of the skin of a subject wearinga device incorporating the optical sensor.

FIG. 2 is a side section view of an optical sensor module having lightguides, according to some embodiments of the present invention.

FIG. 3A is an enlarged, partial view of the distal end of a light guidefrom the optical sensor module of FIG. 2 and which illustrates a curvedconfiguration of the surface of the light guide distal end.

FIG. 3B is an enlarged, partial view of the distal end of a light guidefrom the optical sensor module of FIG. 2 and which illustrates atextured configuration of the surface of the light guide distal end andlight rays emanating from the textured surface.

FIG. 4 is a side section view of an optical sensor module havingmultiple light guides, according to some embodiments of the presentinvention.

FIG. 5 is a graph illustrating the effect on an optical signal from asensor module as a function of distance of the sensor module from thebody of a subject wearing the sensor module.

FIG. 6 is a side section view of an optical sensor module having lightguides, according to some embodiments of the present invention, andillustrating a light detector being moved in an arc above the opticalsource and a light source being moved in an arc above the opticaldetector.

FIG. 7 is a graph illustrating the results of a sweep test asillustrated in FIG. 6 for a sensor module without light guides, for asensor module with light guides with flush, un-textured end surfaces,and for a sensor module with textured end surfaces.

FIG. 8 is a cross sectional view of a ring incorporating an opticalsensor module according to some embodiments of the present invention.

FIG. 9A illustrates an optical sensor module integrated within a mobiledevice and that is configured to engage an optical module worn by auser, according to some embodiments of the present invention.

FIG. 9B is a side section view of the optical sensor and optical moduleof FIG. 9A prior to the optical sensor engaging the optical module.

FIGS. 10A-10B are side section views of an optical sensor module and anoptical module, according to other embodiments of the present invention.

FIG. 11A is a side section view of an optical sensor module, an opticalmodule, and an optical coupler therebetween, according to someembodiments of the present invention.

FIG. 11B is a side section view of an optical sensor module, an opticalmodule, and an optical coupler therebetween, according to someembodiments of the present invention.

FIG. 12A is a front perspective view of an optical sensor module,according to some embodiments of the present invention.

FIG. 12B is a side view of the optical sensor module of FIG. 12Aillustrating the light guides therein angled away from each other.

FIG. 12C is a side view of the optical sensor module of FIG. 12A.

FIG. 12D is a front view of the optical sensor module of FIG. 12A.

FIG. 12E is an end view of the optical sensor module of FIG. 12A.

FIG. 12F is a rear perspective view of the optical sensor module of FIG.12A.

FIG. 13A is a front view of an earbud speaker driver with integratedoptomechanics, according to some embodiments of the present invention.

FIG. 13B is a rear view of the earbud speaker driver of FIG. 13A.

FIG. 13C is a side view of the earbud speaker driver of FIG. 13A.

FIG. 13D is a rear view of the earbud speaker driver of FIG. 13A withthe light guides coupled to a sensor module, according to someembodiments of the present invention.

FIG. 14 is an illustration of a human ear with various portions thereoflabeled.

FIGS. 15-20 illustrate an earbud speaker driver positioned relative toan ear of a subject, according to various embodiments of the presentinvention.

FIGS. 21A-21B and 22A-22B illustrate a speaker driver sensor, accordingto some embodiments of the present invention.

FIGS. 23-25 are block diagrams illustrating various configurations of adata processing unit in communication with an earbud having a sensormodule, according to embodiments of the present invention.

FIG. 26 is a block diagram an earbud having a sensor module and dataprocessing capability, according to some embodiments of the presentinvention.

FIG. 27 illustrates a pair of earbuds which each contain a sensor moduleaccording to embodiments of the present invention, and which are incommunication with a data processing unit.

FIG. 28 illustrates an earbud unit containing a sensor module and a dataprocessing unit, according to some embodiments of the present invention.

FIGS. 29-31 illustrate a speaker driver sensor positioned within an earof a subject, according to some embodiments of the present invention.

FIG. 32A is a side view of a biometric monitoring device, according tosome embodiments of the present invention, and illustrating the centerof gravity of the monitoring device.

FIG. 32B is a front view of the biometric monitoring device of FIG. 32A.

FIG. 32C is a front perspective view of the biometric monitoring deviceof FIG. 32A.

FIG. 32D is a front view of the biometric monitoring device of FIG. 32Aillustrating the intersection of orthogonal planes along which thecenter of gravity of the monitoring device is located.

FIG. 32E is a side view of the biometric monitoring device of FIG. 32D.

FIG. 32F is a front perspective view of the biometric monitoring deviceof FIG. 32D.

FIG. 33 is a top perspective view side section view of an optical sensormodule that includes at least one light polarizing element, according tosome embodiments of the present invention.

FIG. 34 is a side section view of the optical sensor module of FIG. 33.

FIG. 35 is a side section view of an optical sensor module that includesat least one light polarizing element, according to some embodiments ofthe present invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying figures, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Like numbers refer to like elementsthroughout. In the figures, certain layers, components or features maybe exaggerated for clarity, and broken lines illustrate optionalfeatures or operations unless specified otherwise. In addition, thesequence of operations (or steps) is not limited to the order presentedin the figures and/or claims unless specifically indicated otherwise.Features described with respect to one figure or embodiment can beassociated with another embodiment or figure although not specificallydescribed or shown as such.

It will be understood that when a feature or element is referred to asbeing “on” another feature or element, it can be directly on the otherfeature or element or intervening features and/or elements may also bepresent. In contrast, when a feature or element is referred to as being“directly on” another feature or element, there are no interveningfeatures or elements present. It will also be understood that, when afeature or element is referred to as being “connected”, “attached”,“coupled”, or “secured” to another feature or element, it can bedirectly connected, attached, coupled, or secured to the other featureor element or intervening features or elements may be present. Incontrast, when a feature or element is referred to as being “directlyconnected”, “directly attached”, “directly coupled”, or “directlysecured” to another feature or element, there are no interveningfeatures or elements present. Although described or shown with respectto one embodiment, the features and elements so described or shown canapply to other embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

As used herein, the terms “comprise”, “comprising”, “comprises”,“include”, “including”, “includes”, “have”, “has”, “having”, or variantsthereof are open-ended, and include one or more stated features,integers, elements, steps, components or functions but does not precludethe presence or addition of one or more other features, integers,elements, steps, components, functions or groups thereof. Furthermore,as used herein, the common abbreviation “e.g.”, which derives from theLatin phrase “exempli gratia,” may be used to introduce or specify ageneral example or examples of a previously mentioned item, and is notintended to be limiting of such item. The common abbreviation “i.e.”,which derives from the Latin phrase “id est,” may be used to specify aparticular item from a more general recitation.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items and may be abbreviated as“/”.

As used herein, phrases such as “between X and Y” and “between about Xand Y” should be interpreted to include X and Y. As used herein, phrasessuch as “between about X and Y” mean “between about X and about Y.” Asused herein, phrases such as “from about X to Y” mean “from about X toabout Y.”

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

It will be understood that although the terms first and second are usedherein to describe various features or elements, these features orelements should not be limited by these terms. These terms are only usedto distinguish one feature or element from another feature or element.Thus, a first feature or element discussed below could be termed asecond feature or element, and similarly, a second feature or elementdiscussed below could be termed a first feature or element withoutdeparting from the teachings of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

The term “about”, as used herein with respect to a value or number,means that the value or number can vary, for example, by +/−20%, +/−10%,+/−5%, +/−1%, +/−0.5%, or even +/−0.1%.

The term “headset”, as used herein, is intended to include any type ofdevice or earpiece that may be attached to or near the ear (or ears) ofa user and may have various configurations, without limitation. Headsetsincorporating optical sensor modules, as described herein, may includemono headsets (a device having only one earbud, one earpiece, etc.) andstereo headsets (a device having two earbuds, two earpieces, etc.),earbuds, hearing aids, ear jewelry, face masks, headbands, and the like.In some embodiments, the term “headset” may include broadly headsetelements that are not located on the head but are associated with theheadset. For example, in a “medallion” style wireless headset, where themedallion comprises the wireless electronics and the headphones areplugged into or hard-wired into the medallion, the wearable medallionwould be considered part of the headset as a whole. Similarly, in somecases, if a mobile phone or other mobile device is intimately associatedwith a plugged-in headphone, then the term “headset” may refer to theheadphone-mobile device combination.

The terms “optical source” and “optical emitter”, as used herein, areinterchangeable.

The term “monitoring” refers to the act of measuring, quantifying,qualifying, estimating, sensing, calculating, interpolating,extrapolating, inferring, deducing, or any combination of these actions.More generally, “monitoring” refers to a way of getting information viaone or more sensing elements. For example, “blood health monitoring” mayinclude monitoring blood gas levels, blood hydration, andmetabolite/electrolyte levels, etc.

The term “physiological” refers to matter or energy of or from the bodyof a creature (e.g., humans, animals, etc.). In embodiments of thepresent invention, the term “physiological” is intended to be usedbroadly, covering both physical and psychological matter and energy ofor from the body of a creature. However, in some cases, the term“psychological” is called-out separately to emphasize aspects ofphysiology that are more closely tied to conscious or subconscious brainactivity rather than the activity of other organs, tissues, or cells.

The term “body” refers to the body of a subject (human or animal) thatmay wear a device incorporating one or more optical sensor modules,according to embodiments of the present invention.

The term “coupling”, as used herein, refers to the interaction orcommunication between excitation light entering a region of a body andthe region itself. For example, one form of optical coupling may be theinteraction between excitation light generated from an optical sensormodule and the blood vessels of the body of a user. In one embodiment,this interaction may involve excitation light entering the ear regionand scattering from a blood vessel in the ear such that the intensity ofscattered light is proportional to blood flow within the blood vessel.

The term “processor” is used broadly to refer to a signal processor orcomputing system or processing or computing method which may belocalized or distributed. For example, a localized signal processor maycomprise one or more signal processors or processing methods localizedto a general location, such as to a wearable device. Examples of suchwearable devices may comprise an earpiece, a headset, a headpiece, afinger clip/band, a toe clip/band, a limb band (such as an arm band orleg band), an ankle band, a wrist band, a nose band, a sensor patch, orthe like. Examples of a distributed processor include “the cloud”, theinternet, a remote database, a remote processor computer, a plurality ofremote processors or computers in communication with each other, or thelike, or processing methods distributed amongst one or more of theseelements. The key difference is that a distributed processor may includedelocalized elements, whereas a localized processor may workindependently of a distributed processing system. As a specific example,microprocessors, microcontrollers, ASICs (application specificintegrated circuits), analog processing circuitry, or digital signalprocessors are a few non-limiting examples of physical signal processorsthat may be found in wearable devices.

The term “remote” does not necessarily mean that a remote device is awireless device or that it is a long distance away from a device incommunication therewith. Rather, the term “remote” is intended toreference a device or system that is distinct from another device orsystem or that is not substantially reliant on another device or systemfor core functionality. For example, a computer wired to a wearabledevice may be considered a remote device, as the two devices aredistinct and/or not substantially reliant on each other for corefunctionality. However, any wireless device (such as a portable device,for example) or system (such as a remote database for example) isconsidered remote to any other wireless device or system.

Sensor modules, according to embodiments of the present invention may beintegrated into various wearable devices including, but not limited toheadsets (e.g., earbuds, etc.), wristbands, arm bands, leg bands, rings,patches, etc.

Referring to FIG. 2, an optical sensor module 20 that may beincorporated into a wearable device according to some embodiments of thepresent invention is illustrated. The illustrated sensor module 20includes a substrate or base 22 (e.g., a circuit board, etc.) having anoptical source 24 and an optical detector 26. As would be understood byone skilled in the art of the present invention, the base 22 may supportand/or be connected to various electronic components including, but notlimited to, a signal processor, a wireless module for communicating witha remote device, a memory storage device, etc. Moreover, a battery, suchas a lithium polymer battery or other portable battery, may be mountedto or connected to the base 22 and may be charged via a charge port,such as a USB charge port, for example. Additionally, the base 22 may beflexible, may be rigid, or may include a combination of flexible andrigid material. The base 22 may have various configurations suitable forsupporting electronics.

The optical source 24 may be one or more light-emitting diodes (LED),laser diodes (LD), compact incandescent bulbs, micro-plasma emitters, IRblackbody sources, organic LEDs, or the like. The optical detector 26may be one or more photodiodes, photodetectors, phototransistors,thyristors, solid state devices, optical chipsets, or the like.

A housing 30 is secured to the base 22 and overlies the optical source24 and optical detector 26. The illustrated housing 30 has a curvedouter surface 32 that is configured to engage a particular portion ofthe body of a user of the sensor module 20 (i.e., a person wearing adevice incorporating the optical sensor module 20). For example, in someembodiments, the sensor module 20 may be incorporated into an earbud andthe housing outer surface 32 is contoured to matingly engage aparticular region of the ear (e.g., the region between the anti-tragusand the concha, the region along the helix or anti-helix of the ear,etc., as illustrated in FIG. 14). However, the housing outer surface 32may have various shapes and configurations and need not be curved. Forexample, in some embodiments, the outer surface 32 of the housing may beflat such that the sensor module 20 may be integrated within awristband.

The term “matingly engage”, as used herein, does not necessarily meanthat the housing 30 must physically touch the body of the person;rather, “matingly engage” implies that the housing 30 is designed tooptically or optomechanically couple with a particular region of thebody or to have a physical structure that compliments a particularregion of the body. For example, the housing 30 of FIG. 2 may fit wellwithin an audio earbud and support optical coupling between theanti-tragus and concha of the ear, but a flat housing structure may bemore suitable for the housing enabling optical coupling to a person'swrist.

Though FIG. 2 presents a convex (outward-curving) housing 30, a concave(inward-curving) housing 30 may be better suited for other regions ofthe body. For example, a concave housing 30 may be well-suited for adigit or limb of the body. Additionally, a concave housing 30 may bewell-suited for coupling to the ear region behind the ear, adjacent tothe earlobe.

The illustrated housing 30 includes a first light guide 40 in opticalcommunication with the optical source 24 and a second light guide 42 inoptical communication with the optical detector 26. In addition tosupporting the first and second light guides 40, 42, the housing 30 maybe configured to enclose and protect the various electronic componentsmounted to the base 22 from ambient interference (air, humidity,particulates, electromagnetic interference, etc). In some embodiments,the housing 30 may comprise opaque material that prevents light fromescaping or entering the light guides 40, 42 laterally (i.e., confineslight within the light guides 40, 42 such that light only enters andexits through the respective light guide ends). However, embodiments ofthe present invention do not require the housing to comprise opaquematerial.

The first light guide 40 comprises light transmissive materialconfigured to deliver light from the optical source 24 into a region ofa body of a user at one or more predetermined locations. The secondlight guide 40 comprises light transmissive material configured tocollect light external to the sensor module 20 and deliver the collectedlight to the optical detector 26. The first and second light guides 40,42 may be formed from various types of light transmissive material. Insome embodiments, one or both of the first and second light guides 40,42 may be formed from an elastomeric light transmissive material. Inother embodiments, one or both of the first and second light guides 40,42 may be formed from a substantially rigid light transmissive material.In some embodiments, one or both of the first and second light guides40, 42 may be formed from a combination of elastomeric lighttransmissive material and substantially rigid light transmissivematerial. Exemplary light transmissive materials include, but are notlimited to, polycarbonate, acrylic, silicone, glass, metal oxides,polyurethane, etc. In addition, one or both of the first and secondlight guides 40, 42 may comprise one or more optical fibers.

In some embodiments, a physical optical filter may be disposed along theoptical paths R₀ and R_(i) such that only certain wavelengths of lightare allowed to leave or enter the sensor module 20. The physical opticalfilter can be disposed anywhere along the optical path(s), and may beany variety of filters that are well known in the art, as well as new,innovative filters. An optical filter may be composed of polycarbonate,acrylic, silicone, glass, metal oxides, polyurethane, etc. In someembodiments, an optical filter may be a small slab that is placed in theoptical path of the optical source 24 and/or optical detector 26 and maybe supported by the structure of the sensor module 20. In someembodiments, an optical filter may be integrated with the optical source24 and/or the optical detector 26. For example, a bandpass filter, suchas an interference filter or the like, may be disposed on the top of theoptical source 24 and/or optical detector 26. Alternatively (oradditionally), an optical filter effect may be integrated within thesemiconductor material comprising the optical source 24 and/or opticaldetector 26, such as by selective ion implantation of certain regionswithin silicon or by band-gap engineering within compoundsemiconductors, such as the AlInGaAs or AlInGaN system of semiconductorengineering.

In some embodiments, an optical filter may be integrated within one ormore of the light guides 40 and 42. For example, one or both of thefirst and second light guides 40, 42 may comprise a material having anoptically filtering dye or a material which inherently filters one ormore wavelengths of light. As one example, either or both of the lightguides 40 and 42 may comprise, wholly or partially, a dye therewithin.As one specific example, at least one light guide may comprise a dye,such as an infrared dye designed to block visible wavelengths but passIR wavelengths. For example, a polycarbonate or acrylic light guide 40or 42, dyed with Gentex-E800, would facilitate both light-guiding andIR-pass filtering functionality. Alternatively, another example of suchan integrated physical optical filter comprises Filtron® absorptive dyesdispersed in polycarbonate and/or acrylic to create an edge or long-passoptical filter. Such materials may be conventionally molded, extruded,and/or fabricated into an optical filter having a variety of shapes. Inthe case of FIG. 2, at least one light guide may be partially or whollycomprised of such a material, thereby facilitating the combinationalpurpose of light guiding and optical filtering.

A few additional non-limiting examples of an inherently filteringmaterial includes sapphire, which absorbs some infrared (IR)wavelengths, and glass, which absorbs some ultraviolet (UV) wavelengths.However, various types of filtering material may be utilized, withoutlimitation. In some embodiments, one or both of the light guides 40, 42may be surrounded or partially surrounded by a cladding/barrier material(not shown) that is configured to at least partially block light from anexternal source from entering one or both of the light guides 40, 42 atselect locations along the light guides 40, 42 and/or at least partiallyconfine light within one or both light guides 40, 42. Thecladding/barrier material may be a light blocking material and/or alight reflective material and/or a material that has a higher opticalscattering coefficient than the light guiding material of the lightguides 40, 42. For example, the cladding material may be a dark (e.g.,black, etc.) or silver (or other reflective color) coating, a materialwith refractive index that differs from the core light guide material,or a texturized light-scattering material on one or more portions of adistal end surface 40 c, 42 c of one or both of the light guides 40, 42.

The first light guide 40 defines a first axial direction A₁, and thesecond light guide 42 defines a second axial direction A₂, asillustrated in FIG. 2. The first axial direction A₁ of the first lightguide 40 has an angle a1 relative to a plane P₁ defined by a surface ofthe optical source 24 that is less than ninety degrees (90°), and thesecond axial direction A₂ of the second light guide 42 has an angle a2relative to a plane P₂ defined by a surface of the optical detector 26that is less than ninety degrees (90°). As such, the first and secondlight guides 40, 42 are positioned within the housing 30 such that theydiverge outwardly from the housing 30.

In some embodiments of the present invention, one or both of the firstand second light guides 40, 42 may have a generally cylindricalconfiguration. In other embodiments, one or both of the first and secondlight guides 40, 42 may have a generally non-cylindrical configuration,e.g., rectangular, triangular, oval, etc.

Each of the first and second light guides 40, 42 has a respectiveproximal end 40 a, 42 a and an opposite distal end 40 b, 42 b. Theproximal end 40 a of the first light guide 40 is positioned adjacent theoptical source 24, and the proximal end 42 a of the second light guide42 is positioned adjacent the optical detector 26. In the illustratedembodiment, the distal end 40 b, 42 b of the light guides 40, 42 extendsslightly outwardly from the housing 30. However, in other embodiments ofthe present invention, the distal end portion 40 b, 42 b of one or bothlight guides 40, 42 may be substantially flush with the housing 30 ormay even be recessed within the housing 30.

Light guides that extend from the housing 30 (as opposed to light guidesthat are flush with the housing 30) may facilitate a highersignal-to-noise (S/N) ratio for biometrically modulated light vs.unwanted optical scatter, because extended light guides may capture moreof the desired biometric signal and/or may reject more of the unwantednoise. Namely, in PPG, blood flowing through a blood vessel will causeoptical scatter directly or indirectly related to blood flow changes.However, there will also be unwanted optical scatter associated withlight bouncing off (i.e., reflecting off) the skin and other bodytissues in a manner that is not biometrically modulated (i.e., lightthat is not interacting with blood flow changes). The desired signal “S”is comprised of light that is biometrically modulated and the noise “N”is comprised of all other scattered light (such as light scattered byskin, other body tissues, motion artifacts, environmental artifacts,etc.). As will be described later, the shape and angle of the lightguides may help increase the S/N ratio.

Light guides that are flush with the housing 30 (as opposed to lightguides that are extended from the housing 30) may be more aestheticallyappealing to those wearing an earbud, armband, or other wearable deviceform-factor that integrates the sensor module 20. This is because therewill be no substantial protrusions that would make the wearable devicelook much different than a wearable device that does not integrate sucha sensor module. Moreover, there may be a higher degree of wearabilityand comfort associated with flush light guides if there are noprotrusions that may potentially generate discomfort after a period oftime wearing a device incorporating the sensor module 20.

The distal end 40 b, 42 b of each illustrated light guide 40, 42 has arespective exposed end surface 40 c, 42 c that is configured to engage(or be positioned adjacent or near) a portion of the body B of a user.In some embodiments, the end surface 40 c, 42 c of one or both of thelight guides 40, 42 may have a curved configuration. For example, FIG.3A illustrates a rounded end surface 40 c of the first light guide 40 ofthe sensor module 20 of FIG. 2. In other embodiments, the end surface 40c, 42 c of one or both of the light guides 40, 42 may have a flatconfiguration. However, the end surface 40 c, 42 c of one or both of thelight guides 40, 42 may be shaped in a variety of ways to couple lightto and from the body of a user. For example, a rounded surface mayimprove light collection from a wider angle and a flat surface maynarrow the field of view of the light guide. In some cases, a widerfield of view may be important to measure more light from a broaderrange along the body, but in other cases, a narrower view may beimportant to focus the field of view on a specific region of the body.Note that the bottom 40 d of the light guide 40 of FIG. 3A is at anangle with respect to the top 40 c of the light guide 40. Although onlylight guide 40 is illustrated in FIG. 3A, it is understood that theother light guide 42 may have a bottom portion that is at an angle withrespect to a top portion thereof. This alteration of symmetry mayprovide better coupling of light from/to the optical source 24/opticaldetector 26 to/from the respective light guide 40, 42 whilesimultaneously directing the respective light paths at the angles a1 anda2 (FIG. 2).

In some embodiments, the end surface 40 c, 42 c of one or both of thelight guides 40, 42 may be textured with a non-optically smooth finishsuch as an SPI (Society of Plastics Industry) B-1 finish, or the like.However, other finish texturing may be used in accordance withembodiments of the present invention including, but not limited to, SPIA-1, SPI A-2, SPI A-3, SPI B-2, and SPI B-3. However, embodiments of thepresent invention do not require surface texturing of the end surfaces40 c, 42 c.

FIG. 3B illustrates the optical impact of a textured end surface 40 c ofthe light guide 40 of the sensor module 20 of FIG. 2. A textured surfacecan cause a “feathering” or “diffusing” of light from the optical source24, thereby limiting the light that reflects directly from the tissueand into the optical detector 26. A diffuse optical beam may also bemore uniform than a beam of light generated by the optical source 24.Diffused light beams may have an intensity distribution that is lesssensitive to body motion and may be useful in alleviating motionartifacts in scattered light coming from the body and detected by theoptical detector 26. The texturing features in this particular exampleof FIG. 3B were generated with an average texturing feature size smallerthan about 100 μm, and the diameter of the light guide was about 3 mm.

The angled configuration of the first and second light guides 40, 42prevents most or all light from the optical source 24 from directlyreaching the optical detector 26 (i.e., without passing through aportion of the body of a user first) when the outer surface 32 of thehousing 30 is separated from the body of a user, for example, by adistance up to about three tenths of a centimeter (0.3 cm) or more. Thisis illustrated in FIG. 2 wherein the dotted line B is representative ofthe body (i.e., the skin) of a user. Distance D₁ represents the distancefrom the body B to the outer surface 32 of the housing 30. Rays of lightemanating from the optical source are represented by R_(o) and rays oflight detected by the optical detector are represented by R_(i). Thelight rays R_(o) emanating from the optical source 24 do not overlapwith the light rays R_(i) returning to the optical detector 26 over thedistance D_(i), as represented by distance D₂. As such, the lightemanating from the optical source 24 is directed along the mostphysiologically meaningful signal pathway (i.e., through the body B andwithout substantial, unwanted reflection from the body B into theoptical detector 26).

Referring to FIG. 4, a sensor module 20, according to some embodimentsof the present invention, may include multiple optical sources 24 and/ormultiple optical detectors 26 and, as such, multiple light guides 40, 42may be utilized. In the illustrated embodiment of FIG. 4, a respectivelight guide 40 is in optical communication with each of the two opticalsources 24, and a respective light guide 42 is in optical communicationwith each of the two optical detectors 26. The light guides 40, 42 eachhave respective axial directions A₁, A₂ that diverge outwardly, asdiscussed above with respect to FIG. 2. Although FIG. 4 shows lightguide arrays are aligned in line with respect to each other, it shouldbe understood that the arrays of light guides may be distributed acrossa common plane or even in multiple planes, and a linear array is notrequired for embodiments of the present invention.

FIG. 5 illustrates how effective a sensor module, such as the sensormodule 20 of FIG. 2, may be in reducing the effect of noise as a resultof movement of the sensor module 20 relative to the body B of a user.The separation distance between sensor module housing outer surface 32and the body of a user B is represented by D₁ in FIG. 2, and is plottedalong the “X” axis of FIG. 5. The signal detected by the opticaldetector 26 is plotted along the “Y” axis of FIG. 5 and varies with thedistance D₁. The signal is shown in FIG. 5 based on this separationdistance (Sensor-tissue separation distance, mm). When a conventionalsensor module with no light guides is used, the signal onset with smallseparation distances is abrupt (namely, the slope is higher), leading toa substantial amount of motion artifact noise in the physiologicalsignal (represented by curve 50). When the sensor module 20 of FIG. 2 isused with flush, non-textured light guides 40, 42, the signal onset withseparation is much less abrupt (namely, the slope is lower), asillustrated by curve 52. When the sensor module 20 of FIG. 2 is usedwith light guides 40, 42 having respective end surfaces 40 c, 42 c thatare textured, the signal onset with sensor-tissue separation is veryslow (namely, the slope is lowest), leading to much less physiologicalmovement-associated noise, as illustrated by curve 54. FIG. 5illustrates the robustness of the sensor module 20 of FIG. 2 againstnoise in a physiological signal detected by the optical detector 26.Thus, although it is true that curve 50 shows a higher overall signalthan that of curve 52 and 54, the slope of curve 50 is much higher asthe sensor module separates from the skin of the user, showing that theuse of light guides can reduce motion artifacts. Furthermore, generallyspeaking, a higher S/N as well as lower motion artifact sensitivity willresult in the best performing PPG sensor modules.

Referring to FIG. 6, another way to model the robustness of the sensormodule 20 of FIG. 2 against physiological signal noise is to perform a“sweep test”. The sweep test involves sweeping either a light source 60over the optical detector 26 or sweeping an optical detector 62 over theoptical source 24. The response signal(s) of the optical detector 24 asa function of the angle of the light source 60 is recorded and theresponse of the optical detector 62 as a function of the angle of theoptical detector 62 is recorded.

The result of such a sweep test is illustrated in FIG. 7 for a sensormodule without light guides, for a sensor module, such as sensor module20 (FIG. 2) with light guides with flush, un-textured end surfaces 40 c,42 c, and for a sensor module, such as sensor module 20 (FIG. 2) withtextured end surfaces 40 c, 42 c. In FIG. 7, sweep angle in degrees isplotted along the “X” axis, and signal response is plotted along the “Y”axis. In FIG. 7, zero degrees (0°) represents a direction normal(“normal direction”) to the planes P₁, P₂ of the surfaces of the opticalsource 24 and the optical detector 26. Similarly, thirty degrees (30°)in FIG. 7 represents an angle that is 30° between the “normal direction”and the emission angle of the light source used for the sweep test. Ascan be seen with the recorded signal vs. sweep angle, the signal has amuch gentler onset with sweep towards the normal (i.e., 0°) with lightguides (in this case the light guides may be referred to as “lightpipes”) 40, 42 having textured end surfaces 40 c, 42 c, as representedby curve 70, and with light guides 40, 42 with flush, un-textured endsurfaces 40 c, 42 c, as represented by curve 74. Within the angle ofinterest, which are the angles of about ±30°, the signal onset is muchsteeper without the use of light guides, as represented by curve 72.This steep onset in signal is a source of motion-artifact noise that canbe remedied by the use of light guides, according to embodiments of thepresent invention. Note that in FIG. 7 the total overall signal ishighest without light guides, but because the change in signal withangle is so high, the ultimate S/N ratio favors using light guides. Thisis because the noise (N_(m)) resulting from motion artifacts can be manytimes that of the PPG signal associated with biometrically modulatedlight.

FIG. 8 illustrates an embodiment of the sensor module 20 of FIG. 2incorporated into a ring device 80 that is configured to be worn arounda digit of a user, according to some embodiments of the presentinvention. The light guides 40, 42 of the sensor module 20 are angledaway from each other to prevent the overlap of light rays leaving theoptical source 24 from directly entering the optical detector 26. Abattery (e.g., a flexible battery) 84 is located within the band 82 ofthe ring device 80 to provide electrical power to the sensor module 20.

It should be noted that the sensor module 20 may be integrated into thering device 80 in additional ways in accordance with embodiments of thepresent invention. For example, the sensor module 20 may be partiallywithin the ring device 80 rather than wholly within the ring device 80as shown in FIG. 8. Additionally, the light guides 40, 42 may extend orpartially extend the length of the outer-inner diameter length (thelength that is the difference between the outer and inner diameter ofthe ring device 80) or the light guides 40, 42 may protrude from thering device 80 itself. Additional configurations may be used where thelight guides 40, 42 direct light at angles relative to each other (e.g.,angles a1 and a2 illustrated in FIG. 2). Also, it should be noted thatthe ring device 80 may be used for not only a finger ring but for anyappendage or rounded form-factor, such as a digit or limb, such as atoe, arm, wrist, leg, a neck, a waist, and the like. The strap or band82 may have different sizes and/or shapes depending on the location ofdonning (i.e., the location on the body of a subject where the device 80is worn).

Referring to FIGS. 9A-9B, 10A-10B, and 11A-11B, embodiments of thepresent invention utilizing a smartphone 100 or other mobile orelectrical device are illustrated. The illustrated smartphone 100includes an optical sensor module 110 that is in proximity to, orintegrated within, the camera optics of the smartphone 100 or anotheroptical emitter/detector already on the smartphone 100. The opticalsensor module 110 is coupled to an optical module 120 in a wearablestructure 130 (such as an armband, wristband, leg band, ring, etc.).This embodiment can be useful for the case when electronics are notdesired to be within the wearable structure itself—for example, opticalmodule 120 may be optics within a phone armband strap, where thesmartphone 100 may contain all the electronics but may not have theoptomechanics for biometric monitoring itself. The optical sensor module110 may have light guides within it or it may not. For example, asillustrated in FIG. 9B, the optical module 110′ includes only a singlewindow W with perhaps a barrier 112 between the optical source 24 andthe optical detector 26. The barrier 112 may protrude all the way to thesurface of the window W or it may be shorter. The benefit of having thebarrier 112 protrude to the surface of the window W is that doing so mayreduce or eliminate cross-talk between the optical source 24 and opticaldetector 26.

The illustrated optical modules 110, 120, 140 include light guides 40,42 as described above with respect to the sensor module 20 of FIG. 2.When the optical modules 110 and 120 (and 140, when utilized) are inalignment (as expressed by the dotted lines in FIG. 9A), light (e.g.,from the flash associated with the camera of the smartphone 100) can becoupled from the smartphone 100 to the body of the person and back fromthe body to the smartphone 100, such that stable optical monitoring ofthe body can be achieved. The light guides 40, 42 in the optical module120 may be configured to be adjacent or proximate to the skin of a userand may be angled away from each other to prevent the overlap of lightrays leaving the optical sources 24 and directly entering the opticaldetectors 26, as described above.

In the embodiment illustrated in FIGS. 10A-10B, the optical module 120has multiple light guides 40, 42 that align with a respective multiplelight guides 40, 42 of the sensor module 110. The light guides 40, 42 ofthe sensor module 110 are substantially orthogonal to the respectiveoptical emitters 24 and optical detectors 26, as illustrated. However,the light guides 40, 42 of the optical module 120 are angled such thatthey diverge from each other, as illustrated. This angled configurationof the light guides 40, 42 in the optical module 120 prevents most orall light from the optical sources 24 from directly reaching the opticaldetectors 26 without first passing through a portion of the body of auser.

Other coupling configurations and light-guiding configurations for theoptical module 120 may be used in embodiments of the present invention,and the light guides of the module 120 do not need to be angled as shownin FIGS. 10A-10B. However, the benefits of angling have been disclosedherein. Additionally, the light guides 40, 42 may be cylindrical, oval,or elliptical (i.e., have circular, oval, or elliptical cross-sections)to prevent unwanted scattering at the edges. However, havinglight-guiding cross-sections with “sides” or “angles”, such as the casefor polygonal light guide cross-sections, may be useful for matching thecoupling between the modules 110 and 120.

A benefit of the configuration presented in FIG. 9A is that the opticalmodule 120 may reside in a wearable band (or apparel item) 130 withoutany need for supporting electronics or battery power in the wearableband 130, as the optical emission and detection may take place via theelectronics/optics of the electrical device 100 (such as a smartphone,smartwatch, smartearbud, smartsensor, or other electrical apparatus thatis light-weight enough to be attached to and worn on the body of aperson). The wearable band 130 may be a ring, an armband (as shown),wristband, legband, neckband, or any band or apparel item such as anitem of clothing (shirts, socks, under-garments, etc.) that can be wornalong the body but which can also support the optical module 120. Manydifferent kinds of band materials and fabrics may be used, such asplastic, polymers, metals, rubbers, silicones, cotton, nylon, wood, orany other sturdy materials that can be worn for a period of time bysubjects. However, the wearable band 130 should be stabilized along thebody for accurate physiological readings to be assessed on a continuousbasis. This may be achieved by using a stretchable material that can fitfirmly along the body and/or by integrating a securing mechanism such asa buckle, clamp, clasp, button, etc., and/or by employing a springing orclamping method to hold both modules in place along the body, using oneor more body regions for mechanical support. The optical module 120 doesnot need to touch the skin in order to generate physiologicalinformation, but the optical module 120 typically will perform best whenstabilized with respect to the body of the subject.

An additional benefit of the configuration shown in FIG. 9A is that theconfiguration allows for novel biometric sensing use cases via selectivebiometric analysis. Namely, if the electrical device 100 is configuredto have optics 110 that comprises both a camera module (such assmartphone CCD camera optics, for example) as well as PPG module (suchas an optical emitter and an accompanied optical detector), and aprocessor communicating with both the camera module and the PPG module,then advanced biometric sensing may be achieved, such as selectivebiometric analysis. In this methodology, images of the body of thesubject may be collected and analyzed by the processor with respect toblood flow as sensed by the PPG module. For example, the processor mayidentify the frequency of blood flow (i.e., the frequency relating tothe heart rate or breathing rate) via sensor data from the PPG moduleand may analyze images sensed by the camera module with respect to thisfrequency. In this method, pixels that are changing at the same rate (orapproximate same rate) as the blood flow frequency may be selectivelyamplified with respect to pixels that are not changing at this rate(raising the effective contrast). In this way, blood vessels (arteries,veins, arterioles, capillaries, and the like) may be selectivelyanalyzed to generate biometric assessments, even in noisy environments.

According to some embodiments of the present invention, the process canbe executed in reverse such that regions of the body that do notsubstantially modulate with blood flow may be selectively amplified withrespect to regions that do modulate with blood flow. These more staticregions (such as certain tissue regions comprising bone, skin, tendons,etc.) may then be selectively analyzed.

The above-described selective amplification may be further enhanced byincorporating active motion-artifact removal by using a motion sensor(such as an accelerometer or other motion sensor) in physicalcommunication with the body, smart device 100, and/or wearable band as anoise reference such that the processor, in communication with themotion sensor, is able to selectively remove or attenuate frequenciesassociated with body motion or other unwanted motion noise. Because manysmartphones and other smart devices may comprise both digital camerasand accelerometers (often having multiple axes), the processor (whichmay also reside in a smartphone) may have access to all of theseelectronics.

There are several examples of biometric assessments that may begenerated by the selective amplification method described above. Forexample, by ratioing intensities of two (2) or more wavelengths from theselectively amplified pixels, an assessment of blood analyte along eachblood vessel may be generated. An example of such blood analyte mayinclude any optically interacting blood analyte, such as bloodhemoglobin (oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, andmethemoglobin, for example), bilirubin, lactate, glucose, and the like.Numerous blood chromophores may be analyzed via this method. In the caseof glucose and other blood analyte which are not chromophores, addingone or more polarizers to the optics (110, 120) may be required, asglucose and other blood constituents have been observed topreferentially scatter light at certain polarizations. As yet anotherexample of a biometric assessment using selective amplification, aprocessor may analyze blood vessels along their pathways to see how theychange shape with each pulse. This assessment may be used to assessvascular compliance and/or blood pressure along the vessels or to assesscardiac output by assessing these localized blood vessel changes inrelation to a physical model. As yet another example of a biometricassessment using selective amplification, a processor may characterizestatic (not time-varying) and/or dynamic (time-varying) changes in bloodvessels to generate a biometric identification of a subject. In thisassessment, a processor may compare the blood vessel characterizationwith a known characterization stored in memory, for example, by runningan algorithm to assess their similarity. A similarity above a certainthreshold may then trigger an identification for a subject. It isimportant to note that a key aspect of embodiments of the presentinvention is that combining a PPG sensor with a camera affords theability to generate a contrast between physiologicalproperties/characteristics that modulate with blood flow and otherproperties/characteristics that do not substantially modulate with bloodflow.

This selective amplification method may be executed with or withoutmodulating the PPG sensor light source (the optical emitter) or with orwithout polling the PPG detector and/or the camera. For example, a PPGsensor may be operating in a continuous mode, and PPG readings as wellas camera readings may be collected continuously. Alternatively, a PPGsensor may be pulsed to generate pulses of light, or the PPG detector orthe camera readings may be polled at time intervals. If multiplewavelengths are employed with the PPG sensor, then alternatelymodulating (i.e., pulsing) the optical emitters such that only oneemitter is on at a time may help differentiate the PPG signals for eachwavelength. However, this effect may also be achieved by continuouslyemitting all optical emitting wavelengths and differentiating signalsfrom each wavelength via optical filters on the camera and/or theoptical detector(s) of a PPG sensor. For example, the optical detectorsof a PPG sensor may each comprise one or more optical filters to passonly certain wavelengths of light and the camera may comprise opticalfilters and/or may comprise beam-splitting optics to direct certainoptical wavelength ranges to certain light-detecting regions of thecamera.

In some embodiments, an optomechanical coupler 140 (FIGS. 9A and11A-11B) can be used to interface between optical sensor module 110 andoptical module 120 such that the two optical modules 110, 120 can bematched or to provide additional stability between the smartphoneoptical module 110 and the band optical module 120. This may beadvantageous where a smartphone 100 has native optomechanics 110 (suchas the optics used for a photographic camera and/or optics used tomeasure heart rate) that may not directly match with the optomechanicsof the band 120. In this case, the coupling optomechanics 140 can beused to translate between the optics 110 and 120.

In the embodiment illustrated in FIG. 11A, the optomechanical coupler140 has light guides 40, 42 with a similar shape and configuration asthe sensor module 110. In the embodiment illustrated in FIG. 11B, thecoupler 140 has light guides 40, 42 with shapes at one end that conformwith shapes of the light guides 40, 42 of the sensor module 110, andwith different shapes at the opposite end that conform with shapes ofthe light guides 40, 42 of the optical module 120. The coupler 140 isdesigned to couple with the optics on a smart device (illustrated as asmartphone 100 in FIG. 9A) and the optics in the wearable sensor (130,FIG. 9A). As such, a user can utilize a separate coupler 140 for eachsmartphone or other device that they use, since each smartphone/devicemay be manufactured using different optics.

FIGS. 12A-12F illustrate another style of the optical sensor module 20of FIG. 2 that can be used with various wearable monitoring devices,such as earbud monitoring devices. The illustrated sensor module 20includes a substrate or base 22 (e.g., a circuit board, etc.) having anoptical source 24 and an optical detector 26 on one side 22 a thereof.The base 22 may support and/or be connected to various electroniccomponents including, but not limited to, a signal processor, a wirelessmodule for communicating with a remote device, a memory storage device,etc. Moreover, a battery, such as a lithium polymer battery or otherportable battery, may be mounted to or connected to the base 22 and maybe charged via a charge port, such as a USB charge port for example.Additionally, the base 22 may be flexible, rigid, or a combination offlexible and rigid material, or various other base constructs suitablefor supporting electronics. The base 22 may comprise one piece or aplurality of pieces. In the illustrated embodiment, a capacitor 24 c fordriving the optical source 24 and an accelerometer 27 are mounted to anopposite side 22 b of the base 22.

The optical source 24 may be one or more light-emitting diodes (LED),laser diodes (LD), compact incandescent bulbs, micro-plasma emitters, IRblackbody sources, or the like. The optical detector 26 may be one ormore photodiodes, photodetectors, phototransistors, thyristors, solidstate devices, optical chipsets, or the like.

A housing 30 is secured to the base 22 and overlies the optical source24 and optical detector 26. The illustrated housing 30 has a curvedouter surface 32 that is configured to engage a particular portion ofthe body of a user wearing a device incorporating the sensor module 20.For example, although the sensor module 20 may be integrated intonumerous wearable form-factors that afford proximate location of thesensor module to the skin of the user, in some embodiments, the sensormodule 20 may be incorporated into an earbud and the housing outersurface 32 is contoured to matingly engage a particular region of theear (e.g., the region between the anti-tragus and the concha, the regionalong the helix or anti-helix of the ear etc.). However, the housingouter surface 32 may have various shapes and configurations and need notbe curved. For example, a wristband module applying the invention mayhave a flat housing outer surface 32.

The housing 30 includes a first light guide 40 in optical communicationwith the optical source 24 and a second light guide 42 in opticalcommunication with the optical detector 26. In addition to supportingthe first and second light guides 40, 42, the housing 30 may beconfigured to enclose and protect the various electronic componentsmounted to the base 22 from ambient interference (air, humidity,particulates, electromagnetic interference, etc).

The first light guide 40 defines a first axial direction A₁, and thesecond light guide 42 defines a second axial direction A₂. The firstaxial direction A₁ of the first light guide 40 has an angle a1 relativeto a plane P₁ defined by a surface of the optical source 24 that is lessthan ninety degrees (90°), and the second axial direction A₂ of thesecond light guide 42 has an angle a2 relative to a plane P₂ defined bya surface of the optical detector 26 that is less than ninety degrees(90°). As such, the first and second light guides 40, 42 are positionedwithin the housing 30 such that they diverge outwardly from the housing30.

Referring now to FIGS. 13A-13D, an earbud speaker driver 300 withintegrated optomechanics, according to some embodiments of the presentinvention, is illustrated. The speaker driver 300 has opposite front andrear portions 302 a, 302 b. As understood by those skilled in the art,sound is emitted through apertures 306 formed in the front portion 302 aof the speaker driver 300. An optical source 24 and optical detector 26are supported by a printed circuit board (PCB) 304 on the rear portion302 b of the speaker driver 300. Light guides 40, 42 couple from theoptical source 24 and optical detector 26 to a select region of the ear.In one particular embodiment, the light guides lead to a sensor modulethat may be placed between the anti-tragus an concha of the ear, such asthe sensor module 304 in FIG. 13D. The light guides 40, 42 may lead toany region of the ear, such as the ear canal, tympanic membrane,earlobe, helix, anti-helix, tragus, behind the ear, temple, etc.

A key benefit of the illustrated speaker driver 300 of FIGS. 13A-13D isthat all the sensor electronics may be integrated into a compact speakerdriver or speaker driver assembly, rather than dispersed throughout anearbud, and the light guiding may be used to couple from the speakerdriver 300 to numerous locations of the ear. Additional sensorelectronics and light guiding may also be located on the speaker driver300. For example, the PCB 304 may support an accelerometer, humiditysensor, altimeter, proximity sensor, temperature sensor, etc. Moreover,the PCB 304 may house a temperature sensor coupled to a light guide thatdirects black body radiation from the tympanic membrane to thetemperature sensor. In this case, the temperature sensor may preferablycomprise at least one thermopile and one thermistor.

FIG. 14 is an illustration of a human ear E with various portionsthereof labeled. FIGS. 15-17, 18A-18B, 19, 20, 21A-21B and 22A-22B showvarious embodiments of speaker drivers 300 integrated with biometricsensors or both biometric sensors and light guides. It should be notedthat the speaker drivers 300 may be integrated within earbuds or otherearpieces, or other headwear, but the earbuds are not shown to promoteclarity of the invention and to highlight the fact that the speakerdrivers 300 may be integrated into a variety of different earbuds,earpieces, headwear, and the like. Additionally, the sizes of variouselements may not be to scale. For example, light guides (e.g., 40, 42,FIGS. 17, 19) may be shown smaller, larger, differently shaped than maybe in an actual device in order to help present certain aspects of theinvention more clearly in the figures.

In FIGS. 15-20, a speaker driver 300 is shown without an earbud housing,as the speaker driver 300 may be incorporated in a variety of earbuddesigns. The speaker driver 300 is shown positioned within an ear E of asubject and has a sensor circuit 312. In the embodiment illustrated inFIG. 15, the speaker driver 300 is positioned near the concha of the earE, for example between the antihelix and the tragus of the ear E. A flexcircuit (or other electrical connection medium) 310 is electricallyconnected to the speaker driver 300 and extends from the speaker driver300. The flex circuit 310 supports a sensor circuit 312 that includes anoptical emitter 24 and optical detector 26. The flex circuit 310provides a signal path from/to the sensor circuit 312 and speaker driver300. In FIG. 15, the speaker driver 300 is illustrated slightly higherin the concha than would be normal in order to be able to illustrate thesensor circuit 312.

The flex circuit 310 is configured such that sensor circuit 312 touchesthe skin of the ear at a region containing blood vessels, such as theconcha, anti-tragus, ear canal, anti-helix, helix, earlobe, behind theear, and the like. Performance may be best when the sensor circuit islocated at the anti-tragus and/or concha, including (but not limited to)the intersection of the anti-tragus and concha of the ear E. In theillustrated embodiment, the earbud wire 314 (i.e., the electrical wireproviding sound to the earbud speaker driver 300, as well as providingelectrical connectivity to the sensor circuit 312) is connected to theflex circuit 310. The flex circuit 310 is configured to dampen soundvibrations from the speaker driver 300 and to provide tight coupling ofthe sensor circuit 312 to the skin.

In the embodiment illustrated in FIG. 16, the speaker driver 300 ispositioned near the concha of the ear E, for example between theantihelix and the tragus of the ear E. A rigid sensor circuit 312 thatincludes an optical emitter 24 and optical detector 26 is secured to thespeaker driver 300 and is electrically connected to the speaker driver300. In the illustrated embodiment, the sensor circuit 312 is orientedto touch the skin behind the antitragus of the ear E (the skin betweenthe anti-tragus and concha of the ear E), but other locations of the earare also appropriate. Damping material 316 is positioned between thesensor circuit 312 and the speaker driver 300, as illustrated. Thedamping material 316 dampens sound vibrations from the speaker driver300 and provides cushioned coupling with the skin of the ear E. In theillustrated embodiment, the earbud wire 314 is connected to the sensorcircuit 310 and to the speaker driver 300. In FIG. 16, the speakerdriver 300 is illustrated slightly higher in the concha than would benormal in order to be able to illustrate the light guides 40, 42 andsensor circuit 312.

In the embodiment illustrated in FIG. 17, the speaker driver 300 ispositioned near the concha of the ear E, for example between theantihelix and the tragus of the ear E. A sensor circuit 312 thatincludes an optical emitter 24 and optical detector 26 is secured to thespeaker driver 300 and is electrically connected to the speaker driver300. A pair of light guides 40, 42 are in optical communication with theoptical emitter 24 and optical detector 26, and a distal end of each isconfigured to engage the skin behind the antitragus of the ear E. Lightguide 40 guides light from the optical emitter into the skin and lightguide 42 collects light scattered within the ear and delivers this tothe optical detector 26. In some embodiments, damping material (notshown) may be positioned between the sensor circuit 312 and the speakerdriver 300 to dampen sound vibrations from the speaker driver 300. Inthe illustrated embodiment, the earbud wire 314 is connected to thesensor circuit 310. Although only two light guides 40, 42 areillustrated in FIG. 17, it is understood that more than two light guidesmay be utilized.

In the embodiment illustrated in FIG. 18A, the speaker driver 300 ispositioned within the ear E, for example between the antihelix and thetragus of the ear E. A flex circuit 310 containing an optical emitter 24and detector 26 is electrically connected to the speaker driver 300 andextends from the speaker driver 300 into the ear canal. The emitter 24and detector 26 are configured to emit and detect light along the skinof the ear canal and/or the tympanic membrane. As illustrated in FIG.18B, the speaker driver 300 includes pads 320 for electricallyconnecting to the speaker wire and pads for electrically connecting tothe flex circuit 310.

The flex circuit supports a sensor circuit 312 that includes an opticalemitter 24 and optical detector 26. The flex circuit 310 provides asignal path from/to the sensor circuit 312 and speaker driver 300. Theflex circuit 310 is configured to dampen sound vibrations from thespeaker driver 300 and to provide tight coupling of the sensor circuit312 to the skin within the ear canal. In the illustrated embodiment, theearbud wire 314 is connected to the speaker driver 300.

In the embodiment illustrated in FIG. 19, the speaker driver 300 ispositioned within the ear E, for example between the antihelix and thetragus of the ear E. A sensor circuit 312 that includes an opticalemitter 24 and optical detector 26 is secured to the speaker driver 300and is electrically connected to the speaker driver 300. Dampingmaterial 316 is positioned between the sensor circuit 312 and thespeaker driver 300 to dampen sound vibrations from the speaker driver300. A pair of light guides 40, 42 are in optical communication with theoptical emitter 24 and optical detector 26, and the light guides 40, 42are configured to extend into the ear canal and engage the skin in theear canal and/or the tympanic membrane. Light guide 40 guides light fromthe optical emitter into the ear and light guide 42 collects lightscattered within the ear and delivers this to the optical detector 26.In the illustrated embodiment, the earbud wire 314 is connected to thespeaker driver 300. In FIG. 19, the light guides 40, 42 are configuredto direct light linearly between the emitter 24 and detector 26 and theear E. Also, the emitter light is directed towards the concha of the earand the detector collects light scattered by the concha of the ear.

In the embodiment illustrated in FIG. 20, the speaker driver 300 ispositioned within the ear E, for example between the antihelix and thetragus of the ear E. An earbud wire 314 is connected to the speakerdriver 300 and to a sensor circuit 312. The sensor circuit 312 isconfigured to be positioned within the ear canal and includes an opticalemitter 24 and optical detector 26.

FIGS. 21A-21B and 22A-22B further illustrate the speaker driverembodiment of FIG. 20 situated near or inside the ear canal. In FIGS.21A-21B and 22A-22B, the sensor circuit 312 is shown to be configured tobe flexibly placed within the ear canal to couple with the ear canaland/or tympanic membrane. An additional flex connection or wire from theaudio driver may also be available for additional sensors or actuators,such as at least one mechanical or acoustical actuator and/ormicrophones. In FIGS. 22A-22B, a structure or brace is shown to supportthe sensor circuit to keep it integrated together in the ear canal.

FIGS. 23-25 are block diagrams illustrating various configurations of aremote data processing unit 420 in communication with an earbud 400having a sensor module 20, according to embodiments of the presentinvention. In each of the embodiments, the earbud 400 includes a speakerdriver 300 and a sensor module 20, as described above. In each of theembodiments, the data processing unit 420 includes a processor 422,supporting circuitry 424, and a power source 424, such as a battery,capacitor, power regulating circuitry, energy harvesting power source,and/or a connection to an external power source, as would be understoodby one skilled in the art. Data from the sensor module 20 is processedby the data processing unit 420. The data processing unit 420 isconfigured to communicate with another device via wired or wirelesscommunication.

In the embodiment illustrated in FIG. 23, the processor 422 of theremote data processing unit 420 is in analog communication with thespeaker driver 300 and is in digital communication with the sensormodule 20.

In the embodiment illustrated in FIG. 24, the processor 422 of theremote data processing unit 420 is in digital communication with thesensor module 20. The sensor module 20 may include a digital to analogconverter to provide an audio signal to the speaker driver 300.

In the embodiment illustrated in FIG. 25, the processor 422 of theremote data processing unit 420 communicates with the speaker driver 300of the earbud 400 via analog communication with an embedded digitalsignal. In some embodiments, this analog communication may be wired andin others it may be wireless. The embedded digital signal may be“quasi-digital”, as a modulated signal within the analog signal, suchthat both audio information and biometric sensor information areintegrated within the analog signal. Such modulation may be achieved onthe earbud 400 itself (as represented by the “+” sign in FIG. 25) usingmodulation techniques that are well-known by those skilled in the art(see, for example, U.S. Patent Application Publication No. 2014/0140567,which is incorporated herein by reference in its entirety). The dataprocessing unit 420 may be located with the earbud 400 or may be locatedaway from the earbud 400, with analog communication between the dataprocessing unit 420 and the earbud 400. At least part of thefunctionality of the data processing unit 420 may comprise demodulationof the audio+biometric sensor signals, such that each can be addressedseparately for audio communication and biofeedback. The data processingunit 420 may be in wireless or wired communication with an externaldevice or external circuitry. A key benefit of the illustratedembodiment is that it enables the data processing unit 420 to beintegrated within a smartphone or other smart device via the analogaudio jack of the device, with analog communication to the earbud 400.Thus, a separate digital connection to the smart device would not berequired in such a configuration, as both the audio and biometricsignals are modulated and demodulated in an analog fashion.

FIG. 26 is a block diagram of an earbud 400 having both a sensor module20 and data processing capability, according to some embodiments of thepresent invention. The earbud 400 may include a speaker driver 300 and asensor module 20, as described above, and may include a processor 422,supporting circuitry 424, and a power source 424, such as a battery or aconnection area to access an external power source via a port or throughsoldering. Data from the sensor module 20 is processed by the processor422. The processor 422 is configured to communicate with other devices,including another earbud, via wired or wireless communication 428. Theprocessor 422 is in analog communication with the speaker driver 300 andis in digital communication with the sensor module 20.

A key benefit of the embodiment of FIG. 26 is that it enables anintegrated earbud unit. Such a design may fit within a “true wireless”wireless stereo headset, where there are two separate earpiecesavailable for each ear, with each earpiece in wireless communicationwith the other. In such an embodiment, each earpiece may comprise thestructure of FIG. 26, such that each earpiece comprises sensors andsupports audio communication. Moreover, having the driver circuitry,light-guiding, and sensor circuitry integrated as a unit can help reducethe spacing requirements for such a dual-wireless design, where space isfundamentally limited by the size of a subject's ears.

FIG. 27 illustrates a pair of earbuds 400 according to some embodimentsof the present invention. Each earbud 400 includes a speaker driver 300and sensor module 20, as described above. Each earbud 400 is connectedto a remote data processing unit 420, which may include a processor,supporting circuitry, and a power source, as described above. Data fromeach sensor module 20 is processed by the data processing unit and canbe communicated to other devices via wired or wireless communication.

FIG. 28 illustrates an earbud 400 having both a sensor module 20 anddata processing capability, according to some embodiments of the presentinvention. The earbud 400 includes a speaker driver 300 and a sensormodule 20, as described above. The earbud 400 also includes a processor422, supporting circuitry 424, and a power source 426, such as abattery, enclosed within a housing 430. The housing 430 is configured tobe supported by the ear of a subject. Data from the sensor module 20 isprocessed by the processor 422. The processor 422 is configured tocommunicate with other devices via wired or wireless communication. Asdescribed above with respect to FIG. 26, this embodiment may comprisetwo separate earbuds 400 in wireless communication with each other.Moreover, the electronics may be integrated completely with the earbuds400 alone, such that earhooks may not be required.

FIGS. 29-31 illustrate a speaker driver 300 having integrated lightguiding, with sensor locations positioned in various spots within an earE of a subject, according to some embodiments of the present invention.These figures show designs where the light guiding couples between thespeaker driver 300 and sensor module 20, and wherein the sensor module20 is located at various regions of the ear E. The light guiding may besupported by the earbud housing (not shown), by adhesive (such as glueor welding byproducts), overmolding, integrated alignment tabs, or thelike. To simplify the image to emphasize sensor placement, theseparations and barrier regions between the emitter and detectorlight-guiding is not shown (however, examples are provided in FIG. 12and FIG. 13). FIG. 29 shows a configuration where the light is guidedtowards a region of the ear E between the anti-tragus and concha of theear. FIG. 30 shows a configuration where the light is guided between theanti-helix and concha of the ear E. FIG. 31 shows how the light guidingmay be configured, with the sensor module removed for clarity. The lightguiding may also be contoured to couple from the sensor elements on thespeaker driver 300 to the concha of the ear or other ear location.

In some embodiments, one or both of the light guides 40, 42 may besurrounded or partially surrounded by a cladding/barrier material 112that is configured to at least partially block light from an externalsource from entering one or both of the light guides 40, 42 at selectlocations along the light guides 40, 42 and/or at least partiallyconfine light within one or both light guides 40, 42. Thecladding/barrier material 112 may be a light blocking material and/or alight reflective material and/or a material that has a higher opticalscattering coefficient than the light guiding material of the lightguides 40, 42. For example, the cladding material 112 may be a dark(e.g., black, etc.) or silver (or other reflective color) coating, amaterial with refractive index that differs from (i.e., is less than)the core light guide material, or a texturized light-scattering materialon one or more portions of a distal end surface 40 c, 42 c of one orboth of the light guides 40, 42.

FIGS. 32A-32F illustrate a biometric monitoring device 200 configured tobe secured within an ear of a user and that may incorporate the sensormodule 20 and light guides 40, 42 described above. The illustrateddevice 200 includes an earpiece body 202, a sensor module 204, astabilizer 206, a sound port 208, and a connection point 210. The sensormodule 204 includes angled light guides 40, 42 as described above withrespect to FIG. 2. The illustrated device 200 is configured to bepositioned within an ear of a user so as to reduce movement of thedevice 200. The various components are designed to matingly engage withspecific contact points within an ear. For example, the sensor module204 is configured to engage the region between the anti-tragus andconcha of the ear and the stabilizer is configured to engage theanti-helix.

The illustrated device 200 is designed such that its center of gravityCG (FIGS. 32A-32C) is positioned at a location that provides enhancedstability to the device 200 when positioned within an ear of a user. Theillustrated location of the CG helps prevent the device 200 frombecoming dislodged from an ear of a user during user movement, includingextreme activities, such as running and exercising. Moreover, thelocation of the CG is such that the device 200 is resistant to rotationwhen positioned within the ear of a user.

The center of gravity CG of the illustrated device 200 is located alongthe intersection of orthogonal planes PL1 and PL2 (FIGS. 32D-32F). Asillustrated, plane PL2 bisects the center of the sensor module 204 and,in this particular embodiment, the center of gravity CG of the device200 goes through the middle of the anti-tragus/concha divide in the ear,where the sensor module 204 of the monitoring device 200 is aligned.

FIGS. 33 and 34 illustrate an optical sensor module 20 that can be usedwith various monitoring devices in proximity to the skin, such asmonitoring devices that are integrated into earbuds, armbands,wristbands, rings, patches, eyewear, headbands, and the like, accordingto some embodiments of the present invention. The illustrated sensormodule 20 includes a substrate or base 22 (e.g., a circuit board, etc.)having an optical source 24 and an optical detector 26 on one side 22 athereof. The base 22 may support and/or be connected to variouselectronic components including, but not limited to, a signal processor,a wireless module for communicating with a remote device, a memorystorage device, etc. Moreover, a battery, such as a lithium polymerbattery or other portable battery, may be mounted to or connected to thebase 22 and may be charged via a charge port, such as a USB charge portfor example. Additionally, the base 22 may be flexible, or rigid, or maybe formed from a combination of flexible and rigid material, or variousother base constructs suitable for supporting electronics. In theillustrated embodiment, a capacitor 24 c for driving the optical source24 and an accelerometer 27 are mounted to an opposite side 22 b of thebase 22.

The optical source 24 may be one or more light-emitting diodes (LED),laser diodes (LD), organic light-emitting diodes (OLEDs), compactincandescent bulbs, micro-plasma emitters, IR blackbody sources, or thelike. The optical detector 26 may be one or more photodiodes,photodetectors, phototransistors, thyristors, solid state devices,optical chipsets, or the like.

A housing 30 is secured to the base 22 and overlies the optical source24 and optical detector 26. The illustrated housing 30 has a curvedouter surface 32 that is configured to engage a particular portion ofthe body of a user of the sensor module 20. For example, in someembodiments, the sensor module 20 may be incorporated into an earbud andthe housing outer surface 32 is contoured to matingly engage aparticular region of the ear (e.g., the region between the anti-tragusand the concha, the region along the helix or anti-helix of the ear, theskin of the ear canal, etc.). However, the housing outer surface 32 mayhave various shapes and configurations and need not be curved. Forexample, a wristband module applying the invention may have a flathousing outer surface 32.

The housing 30 includes a first light guide 40 in optical communicationwith the optical source 24 and a second light guide 42 in opticalcommunication with the optical detector 26. In addition to supportingthe first and second light guides 40, 42, the housing 30 may beconfigured to enclose and protect the various electronic componentsmounted to the base 22 from ambient interference (air, humidity,particulates, electromagnetic interference, etc).

The housing 30 also includes a first light polarizing element 90 inoptical communication with the optical source 24, and a second lightpolarizing element 92 in optical communication with the optical detector26. The first polarizing light element 90 is configured to polarizelight emitted by the optical source 24, and the second light polarizingelement 92 is configured to polarize light detected by the opticaldetector 26. Although illustrated as first and second light polarizingelements 90, 92, in some embodiments, the sensor module 20 may utilize asingle polarizing element that is in optical communication with one orboth of the optical source 24 and optical detector 26.

In some embodiments, the first and second light polarizing elements 90,92 have the same light polarization orientation (i.e., parallel planesof polarization). In other embodiments, the first and second lightpolarizing elements 90, 92 have respective different light polarizationorientations. For example, the first and second light polarizingelements 90, 92 may have planes of polarization that are orthogonal(i.e., 90°) to each other.

In some embodiments, one or both of the first and second lightpolarizing elements 90, 92 may be a light polarizing film. In otherembodiments, one or both of the first and second light polarizingelements 90, 92 may be a light polarizing lens. In other embodiments,one or both of the first and second light guides 40, 42 may includelight polarizing material that serves the function of light polarizingelements 90, 92.

The illustrated sensor module housing 30 includes first and secondwindows 33 a, 33 b of optically transparent material through which lightfrom the optical source passes and through which light detected by theoptical detector passes, respectively. In some embodiments, the materialof one or both of the first and second windows 33 a, 33 b may includepolarizing material (e.g., a polarizing film, etc.) that serves as apolarizing element. One or both of the first and second windows 33 a, 33b may also be configured to act as a lens.

In the illustrated embodiment of FIG. 34, the first and second lightpolarizing elements 90, 92 are polarizing films. Light L_(e) emitted bythe optical source 24 is polarized via the first light polarizingelement 90, enters the skin S of a subject being monitored via thesensor module 20 and exits the skin S as modulated light L_(m). Themodulated light L_(m) is polarized via the second light polarizingelement 92 prior to entering the light detector 26. Some of thepolarized light emitted by the light source 24 is reflected off(indicated by L_(r)) of the skin S of the subject. The second lightpolarizing element 92 suppresses this reflected light L_(r). Themodulated light L_(m) that exits the skin S of the subject tends to bedepolarized, and up to 50% of this light will traverse the second lightpolarizing element 92. In principle, light that is specularly reflectedoff the skin, which will have little if any desired blood flow (or otherphysiological) information about the subject wearing the module 20, willbe sharply attenuated by a cross-polarization orientation of the firstand second light polarizing elements 90, 92, with at least one of thefirst and second polarizing elements 90, 92 being off-axis with theother by approximately 90-degrees. Thus, during times of high skinmotion, such as during running or during other aggressive exercise bythe subject wearing the sensor module 20, specularly reflected motionartifacts may be attenuated such that mostly optical scatter signalsfrom below the skin S will reach the optical detector 26.

Any suitable light polarizing material which will produce a lightpolarization effect may be utilized as the first and second lightpolarizing elements 90, 92 in the context of the present invention.Exemplary polarizing material that can be used in accordance withembodiments of the present invention is available from AmericanPolarizers, Inc., Reading, Pa., as well as Edmund Optics, Barrington,N.J.

The light-guiding material itself, or the lens material, may comprisepolarizing material. Additionally, it should be noted that in someembodiments the polarizing material 90, 92 should be located on theoutside of the light guides 40, 42 (as shown in FIG. 35), as thelight-guiding itself may be depolarizing, depending on the material usedand the structure of the light guide, and hence defeat the purpose ofhaving polarizers at all. In such case, a polarization coating or filteron top of each light guide 40, 42 may be most effective. Such a film canbe deposited, textured (etched, machined, imprinted, etc.), laminated,glued, or the like.

Referring now to FIG. 35, a sensor module 20 configured to be worn by asubject according to other embodiments of the present invention isillustrated. The sensor module 20 includes a housing 30 that supports anoptical source 24 and an optical detector 26. A barrier 112 may belocated between the optical source 24 and the optical detector 26 toreduce or eliminate cross-talk between the optical source 24 and opticaldetector 26. The housing also supports a first light polarizing element90 in optical communication with the optical source 24 that isconfigured to polarize light emitted by the optical source 24, and asecond light polarizing element 92 in optical communication with theoptical detector 26 that is configured to polarize light detected by theoptical source 24. The sensor module 20 may have a similar constructionas the sensor module 20 of FIG. 34.

In some embodiments, the first and second light polarizing elements 90,92 have the same light polarization orientation (i.e., parallel planesof polarization). In other embodiments, the first and second lightpolarizing elements 90, 92 have respective different light polarizationorientations. For example, the first and second light polarizingelements 90, 92 may have planes of polarization that are orthogonal(i.e., 90°) to each other.

In some embodiments, one or both of the first and second lightpolarizing elements 90, 92 may be a light polarizing film. In otherembodiments, one or both of the first and second light polarizingelements 90, 92 may be a light polarizing lens which may couple to lightguides (not shown). In other embodiments, the housing 30 may includefirst and second windows as described above with respect to FIG. 34. Insome embodiments, the first and second windows may include polarizingmaterial that serve as the polarizing elements 90, 92.

The illustrated sensor module 20 is secured to a portion of the body Bof a subject via a band or strap 34. For example, the body portion B maybe a digit, an arm, a leg, a torso, etc., of a subject. Light L_(e)emitted by the light source 24 traverses the light polarizing element 90and either enters the body B or is reflected off of the surface of thebody B. Light that enters the body B scatters multiple times, and isbecomes depolarized L_(m), such that when it exits the wrist, much ofthe light L_(m) can traverse the second light polarizing element 92 andbe detected by the light detector 26. Reflected light L₁ can be filteredout by the second light polarizing element 92 and can therefore be keptfrom the light detector 26. As such, the light detector 26 can detectprimarily light from the light source 24 that has travelled through thetissue of the body B.

Any suitable light polarizing material which will produce a lightpolarization effect may be utilized as the first and second lightpolarizing elements 90, 92 in the context of the present invention.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. The invention is defined by the following claims, withequivalents of the claims to be included therein.

1-2. (canceled)
 3. An optical sensor module for detecting and/ormeasuring physiological information from a subject, comprising: a basecomprising an optical source and an optical detector; and a housingconfigured to be integrated within a wearable device and secured to thebase and overlying the optical source and optical detector, wherein thehousing comprises a first light guide in optical communication with theoptical source and a second light guide in optical communication withthe optical detector, wherein the first and second light guides definerespective first and second axial directions, and wherein the first andsecond axial directions diverge outwardly from the housing.
 4. Theoptical sensor module of claim 3, wherein, when the sensor module is inuse and placed adjacent the skin of a subject, the first and secondlight guides are angled relative to each other such that light raysemanating from the optical source and directed into the skin of thesubject via the first light guide cannot overlap with light rayscollected by the second light guide when the housing is separated fromthe skin by a distance up to about three tenths of a centimeter (0.3cm).
 5. The optical sensor module of claim 3, wherein the first axialdirection of the first light guide is angled relative to a plane definedby the optical source, and wherein the second axial direction of thesecond light guide is angled relative to a plane defined by the opticaldetector.
 6. The optical sensor module of claim 3, wherein at least oneof the first and second light guides comprises optical filteringmaterial.
 7. The optical sensor module of claim 3, wherein the first andsecond light guides each comprise opposite proximal and distal ends, andwherein the proximal and distal ends of at least one of the first andsecond light guides have different sizes and/or wherein the proximal anddistal ends of at least one of the first and second light guides havedifferent configurations.
 8. The optical sensor module of claim 3,wherein at least one of the first and second light guides iscylindrical.
 9. The optical sensor module of claim 3, wherein at leastone of the first and second light guides is non-cylindrical.
 10. Theoptical sensor module of claim 3, wherein the first and second lightguides each comprise opposite proximal and distal ends, and wherein thedistal end of at least one of the first and second light guides has acurved surface and/or wherein the distal end of at least one of thefirst and second light guides has a textured surface.
 11. A headset,comprising: an optical source; an optical detector; and a housingsupporting the optical source and optical detector, wherein the housingis configured to be positioned within an ear of a subject, wherein thehousing comprises a first light guide in optical communication with theoptical source and a second light guide in optical communication withthe optical detector, wherein the first and second light guides definerespective first and second axial directions, and wherein the first andsecond axial directions are outwardly diverging.
 12. The headset ofclaim 11, wherein the first light guide comprises a distal endconfigured to deliver light from the optical source into the ear, andwherein the second light guide comprises a distal end configured tocollect light from the ear and deliver collected light to the opticaldetector.
 13. The headset of claim 11, wherein the first and secondlight guides are angled relative to each other such that light raysemanating from the optical source and directed into the ear of thesubject via the first light guide cannot overlap with light rayscollected by the second light guide even when the housing is separatedfrom the ear by a distance up to about three tenths of a centimeter (0.3cm).
 14. The headset of claim 11, wherein at least one of the first andsecond light guides comprises optical filtering material.
 15. Theheadset of claim 11, wherein the first and second light guides eachcomprise opposite proximal and distal ends, and wherein the proximal anddistal ends of at least one of the first and second light guides havedifferent sizes and/or wherein the proximal and distal ends of at leastone of the first and second light guides have different configurations.16. The headset of claim 11, wherein the first and second light guideseach comprise opposite proximal and distal ends, and wherein at least aportion of a distal end of one or both of the first and second lightguides extends outwardly from the housing.
 17. The headset of claim 11,wherein at least one of the first and second light guides iscylindrical.
 18. The headset of claim 11, wherein at least one of thefirst and second light guides is non-cylindrical.
 19. The headset ofclaim 11, wherein the first and second light guides each compriseopposite proximal and distal ends, and wherein the distal end of atleast one of the first and second light guides has a curved surfaceand/or wherein the distal end of at least one of the first and secondlight guides has a textured surface.
 20. A monitoring device,comprising: a band capable of at least partially encircling a portion ofa body of a subject; and an optical source and an optical detectorsupported by the band; wherein the band comprises a first light guide inoptical communication with the optical source and a second light guidein optical communication with the optical detector, wherein the firstand second light guides define respective first and second axialdirections, and wherein the first and second axial directions divergeoutwardly from the band.
 21. The monitoring device of claim 20, whereinthe first and second light guides are angled relative to each other suchthat light rays emanating from the optical source and directed into theskin of the subject via the first light guide cannot overlap with lightrays collected by the second light guide even when the housing isseparated from the ear by a distance up to about three tenths of acentimeter (0.3 cm).
 22. The monitoring device of claim 20, wherein thefirst axial direction of the first light guide is angled relative to aplane defined by the optical source, and wherein the second axialdirection of the second light guide is angled relative to a planedefined by the optical detector.
 23. The monitoring device of claim 20,wherein at least one of the first and second light guides comprisesoptical filtering material.
 24. The monitoring device of claim 20,wherein the first and second light guides each comprise oppositeproximal and distal ends, and wherein the proximal and distal ends of atleast one of the first and second light guides have different sizesand/or wherein the proximal and distal ends of at least one of the firstand second light guides have different configurations.
 25. Themonitoring device of claim 20, wherein at least one of the first andsecond light guides is cylindrical.
 26. The monitoring device of claim20, wherein at least one of the first and second light guides isnon-cylindrical.
 27. The monitoring device of claim 20, wherein thefirst and second light guides each comprise opposite proximal and distalends, and wherein the distal end of at least one of the first and secondlight guides has a curved surface and/or wherein the distal end of atleast one of the first and second light guides has a textured surface.28. The monitoring device of claim 20, wherein the portion of the bodycomprises a limb, a nose, an earlobe, and/or a digit.
 29. The opticalsensor module of claim 3, further comprising: at least one lightpolarizing element in optical communication with the optical source andthe optical detector, wherein the at least one polarizing element isconfigured to polarize light emitted by the optical source and polarizelight detected by the optical detector.
 30. The optical sensor module ofclaim 29, wherein the at least one light polarizing element comprises afirst light polarizing element in optical communication with the opticalsource and a second light polarizing element in optical communicationwith the optical detector.
 31. The optical sensor module of claim 30,wherein the first and second light polarizing elements have the samelight polarization orientation.
 32. The optical sensor module of claim30, wherein the first and second light polarizing elements haverespective different light polarization orientations.
 33. The opticalsensor module of claim 29, wherein the at least one light polarizingelement is a light polarizing film or a light polarizing lens.
 34. Theoptical sensor module of claim 29, wherein the housing comprises atleast one window through which light from the optical source passesand/or through which light detected by the optical detector passes, andwherein the at least one window comprises the at least one polarizingelement. 35-47. (canceled)